Here's a show that has been a cult phenomenon ever since it premiered in London 18 year ago and on Broadway two years later - a show whose fans are easily the musical theater's answer to Trekkies and a musical that made an unlikely icon out of Michael Crawford, its star.

But based on the new movie version of the musical, which is curiously stiff and antic at the same time, it's difficult to grasp exactly why anyone would become obsessed with it. Obviously, I never saw "The Phantom of the Opera" on stage. For some reason, I avoided it, along with "Cats" and "Les Miserables." Which is odd because I generally like musicals.

Or, at least, I did at one time.

The modern stage musical, of which "The Phantom of the Opera" is apparently a prime example, has taken on "event" status in order to survive, while your infrequent contemporary movie musical is now being made to appeal to people who don't like musicals. As much as I both admired and enjoyed Baz Luhrmann's "Moulin Rouge!" (2001) and Rob Marshall's "Chicago" (2002), I resent the weakness exhibited by their respective makers - their lack of belief in the genre (perhaps the only film genre to encompass every possible art and craft) and the ways in which each one tried to disguise his film's true identity. Luhrmann used rapid-fire editing to keep his film hectic and us overwhelmed, while Marshall couched his songs in easy-to-take fantasy.

Heaven forbid that characters on screen should pour their hearts and souls into a song or express themselves by dancing. But to its credit, that's exactly what "The Phantom of the Opera" does. In that sense, it is an old-fashioned movie musical - and an antidote to the gutlessness of "Moulin Rouge!" and "Chicago." It has a story driven by its songs and it isn't afraid to stop dead in its tracks for a big, splashy production number or to let one of its characters step out of the story and look directly into the camera - and, by extension, at us - and simply sing.

It's just too bad that the film isn't better - and too bad that just about every song in Andrew Lloyd Webber's score sounds alike and that Lloyd Webber resorts to the same musical strains he used in "Evita."

Given the overall weakness of the material, director Joel Schumacher works beyond the call of duty to pull us into his musical fable. Schumacher's chief strength here is his eye for casting. He has managed the rare feat of matching the right actor with the right role and, as a result, despite one crucial age discrepancy that doesn't make sense, his film is well-acted and especially well-sung.

He also brings a heightened sense of theatricality to his film that works less as a horror musical than as a bombastic, colorful look at backstage life.

The film opens in Paris in 1919 as an auction is unfolding at that city's Opera Populaire, which is now old and dusty and falling apart. An elderly man, Vicompte Raoul de Chagny (Patrick Wilson in old-age makeup), successfully bids on an antique music box, while being eyed by the elderly Meg Giry (Miranda Richardson, also aged for this sequence).

The film then flashes back to 1870 when the Opera Populaire was a bustling, vital place, full of music - and reportedly haunted by a proprietary ghost, known as the Phantom of the Opera, a specter who behaves like a stage mother toward one of the company's ingénues, chorus girl Christine Daae (Emmy Rossum).

The theater's owners (Simon Callow and Ciarán Hinds, both delightful) have their hands full with the resident diva, La Carlotta (Minnie Driver, who plays the role with animated glee).

The Phantom (Gerard Butler) isn't a ghost at all but a flesh-and-blood man who lives in a lair inside the theater. He had a tragic childhood, full of abuse (well-documented in a flashback), and has been left with a partially disfigured face. He wears half a mask as a result - even though no one ever gets to see him.

The Phantom sabotages La Carlotta during one of her rehearsals and she walks off in a huff, leaving young Christine available for the star role. She's magnificent, natch. Seated in the audience is Raoul (Wilson, without the geriatric makeup), who recognizes Christine as the girl he loved when they were kids. This is where the age problem comes in. Rossum was only 17 when she made "The Phantom of the Opera," while Wilson (from HBO's "Angels in America") was 30 and looks it. So how on earth could these two possibly have been childhood sweethearts? (Butler is 34, but the Phantom is supposed to be somewhat older than Christine, given his role as her self-proclaimed mentor.)

On the sidelines are the young Meg Giry (played by Jennifer Ellison) and her mother, Madame Giry (Richardson again, limning a dual role here), the company ballet mistress who, as a young woman, rescued the boy who would become the Phantom from his cruel, expoiting caregiver and hid him at the Opera Populaire.

Rossum, who made her mark in Maggie Greenwald's "Songcatcher" (2000) and played Sean Penn's murdered daughter in Clint Eastwood's "Mystic River" (2003), is a real find as Christine. Trained at New York's Metropolitan Opera, she is pitch-perfect in voice, looks and acting ability. The film is unimaginable without Rossum.

However, it's the wildly charismatic Butler who rivets us and keeps us spellbound. The handsome Scottish actor (soon to be seen opposite Emily Mortimer in the affecting "Dear Frankie") brings a decided hunk quality to the role of the Phantom and will break your heart during the sweet moment when he sings a bit of a song called "Masquerade" and then glances at Christine and softly tells her that he loves her.

Butler's poignant performance here, backed by Schumacher's solid work, reminds us of how good "The Phantom of the Opera" can be - and also how much better it could have been.